The capacity of probation officers to keep close track of offenders under house arrest was enhanced by the invention set forth in U.S. Pat. No. 5,731,757. The system described in this patent provided for the use of a global positioning system (GPS) to determine the position of a portable tracking apparatus adapted to communicate with an offender's body-worn device. The portable tracking apparatus communicates with a central data base or monitoring station and sends and receives wireless signals from the offender's body-worn device. The portable tracking device warns the offenders if he deviates from a programmed circle of travel, the central data base being able to provide warnings to a potential victim if the subject offender violates a zone of protection. While this system works well, a need has arisen for a simple house arrest system that in addition to tracking, can be provided to law enforcement agencies at a reduced cost.